Japanese Beetle Location
The Japanese beetle was first noticed in this country in 1916, near Riverton, N. J. Presumably it came from its native Japan as a grub in soil around the foots of nursery stock, or perhaps in a shipment of iris or azaleas. Since its discovery this pest has spread naturally from five to ten miles a year, to cover from Maine to Georgia, and west to Michigan and Missouri.
Adult beetles feed on foliage, flowers and fruits of almost 300 plants, and grubs work on grass roots. Some of the beetle’s favorite foods include: shade trees such as elm, horse chestnut, linden, sassafras, white birch, willow; fruits – grapes, raspberries, peach, apple, plum, cherry, quince; flowers – rose, hollyhock, marigold, mallow, spiraea, zinnia; vines – especially Virginia creeper; vegetables – corn, soybean, asparagus, rhubarb.
Japanese Beetle Appearance and Habits
The beetles are about 1/2″ long, shining bronze-green, with bronze wing covers from under which protrude twelve tufts of white hairs. They are particularly active on warm days, congregating in crowds on the sunniest parts of plants. They are most active on warm, sunny days, and fly only in the daytime. They emerge in late spring and early summer, and are most active for four to six weeks. Seasons following a particularly wet summer usually bring a bigger population of beetles.
During this time, each female lays from 40 to 60 eggs 2 to 6 inches deep in the soil. The young grubs feed on grass roots until cold weather, when they work their way down below the frost line. The grubs are white, hairy, brown-headed 3/4 in. long.
Beetles leave only the veins of leaves, and devour entire flower and fruits. Grubs cut off grass roots so that the sod can be rolled back like a carpet. Beetles feeding on corn silks prevent pollination, resulting in sparse kernel development.
How to Manage Japanese Beetles
The Japanese beetle has many natural enemies: the spring and fall typhia wasps, birds, and skunks are helpful beetle enemies.
Avoid planting turf or sod from outside the area, which may lack the nutrients to support these natural enemies.
Milky spore disease is harmless to plants, animals, and humans, but deadly for the beetle. It is most effective in areas bigger than one acre. Talk to a local garden group or county representative for more information.
Remove diseased fruit from the trees and ground, and keep the area weeded and clean.
Larkspur is poisonous for the beetles, and they avoid the odor of geraniums.
Handpick the beetles and drop them into a bucket of water with a think layer of kerosene.
Traps painted yellow and baited with fermenting fruit, sugar, and water catch thousands of beetles – empty this daily.